I can reproduce this kind of problem of the disappearance of a custom tonality system.
Please create your new custom tonality system( custom accidentals and custom key signatures) and save it as default (press Save As Default in Edit Tonality System dialog). Then close the project.
Then create a new project, enter some notes, and enter the custom key signature and custom accidentals to it using the custom tonality system you created last time (do not edit this custom tonality system this time). Then save and close the project, and quit Dorico.
Then open this project in a different environment using a different userlibrary.xml (for example, a different version of Dorico, Dorico owned by someone else, or Dorico with your own userlibrary.xml deleted).
Then you should have this problem. Your custom tonality system disappears and your custom key signatures and accidentals that are present in your score do not appear in the right panel. I think it’s a bug.
I think this is also the cause of the disappearance of the custom tonality system talked about in this topic.
Also, the file (crash.dorico.zip) in this post are in the same problematic state. When we select a note with an accidental in this project, neither the key signatures nor the accidentals appear in the right panel.
